1. Field of the Invention
This invention relates to a catalyst material of carbon black powder having nitrogen affixed to its surface suitable for use as a fuel cell catalyst support, particularly, acid resistant catalyst support for use in phosphoric acid fuel cells, and process for its production, and. The catalyst support of this invention is provided by affixing nitrogen to the surface of carbon black particles by contacting carbon black powder with nitrogen containing ions.
2. Description of Related Art
Improvement of cathode operating voltage and increase of cathode life in lithium sulfuryl chloride electrochemical cells by pretreatment of carbon black powder with acetone or methanol prior to cathode fabrication is known from U.S. Pat. No. 4,526,881.
Plasma activation of catalysts, such as chromium oxide for polymerization of ethylene, by passing an activating gas, such as air or nitrogen, through an electromagnetic field forming a plasma which is contacted with the catalyst at ambient or below temperature and pressure, is taught by U.S. Pat. No. 3,485,771.
Platinum ion implantation in carbon black by high energy ion beams to enhance the catalytic activity for oxygen reduction in phosphoric acid is taught by V. Jalan, Desai, M. and Vora R., Enhanced Catalytic Activity for O.sub.2 Reduction in Phosphoric Acid Using Platinum Implanted Carbons, Extended Abstract, The Electrochemical Society, 891, 893, (1989). This paper teaches that catalytic activity by platinum ion implantation in carbon was greater than with chemically deposited platinum, and in the order of that of heat treatment of platinum supported on carbon. Ion implantation of nitrogen in carbon powder by a high energy nitrogen ion beam was shown to enhance oxygen reduction in phosphoric acid as compared to equivalent mass loadings of chemically deposited platinum by V. Jalan, Desai, M., and Greenwald, A. C., N-Implanted Carbon Catalysts for Oxygen Reduction in Phosphoric Acid, Extended Abstracts, The Electrochemical Society, 89-1, 895, (1989). Ion implantation of nitrogen and transition metals, such as platinum, in carbon blacks changes the crystal structure and the chemical composition of the carbon black target material is taught by M. Desai, Greenwald, A. and Jalan, V., Electrochemistry of Ion-Implanted Carbon Blacks, Extended Abstracts, Proceedings of the Electrochemical Society Meeting, Seattle, Wash., U.S.A., (1990). This paper teaches the corrosion resistance of nitrogen-implanted carbon black to be about an order of magnitude greater than non-implanted carbon black and postulated formation of C--N and Pt--C compounds due to the high energy of each atom which enables formation of unique chemical mixtures and atomic structures.